1. Field of the Invention
This invention relates to a torsion adjusting structure of a screwdriver, particularly to one assembled in the interior of the handle of a screwdriver, able to adjust torsion value of a screwdriver by turning around a regulating knob assembled at the rear end of the handle and also having a function to carry out torsion micro-adjustment after the torsion value is set.
2. Description of the Prior Art
A conventional screwdriver for locking and loosening screws has a handle and a screwdriver shank immovably combined together. In most cases, a person employing such a conventional screwdriver does not know the torsion value which a screw is able to support and turns the screwdriver with force as he pleases. As a result, if the screwdriver is turned with an excessive force, the threads of the screw may get stripped or the recessed groove of the screw head may be damaged, thus causing the screw impossible to be loosened or locked. Another conventional screwdriver adjustable in torsion, as disclosed in a Taiwan utility model patented no. TWM306166, titled “Screwdriver with Fixed Torsion”, includes a handle, a torsion member, a guiding-driving device, a stop piece and a sealing cover combined together. The torsion member consists of an elastic member and a slide block, and the elastic member is correspondingly received in an accommodating space of the handle and the slide block has its peripheral side formed with guide rails corresponding with the guide grooves of the handle so that the slide block can be exactly guided to slide in the accommodating space of the handle and stop the elastic member. The guiding-driving device is composed of a guiding piece and a driving rod, which are oppositely combined together. The driving rod has one end formed with a driving end to be orderly inserted through an insert hole of the slide block and the jointing holes of both the torsion member and the handle. The guiding piece is provided with a pushed face corresponding with the guiding pushing face of the slide block, and the driving rod and the guiding piece have their relative ends respectively formed with a positioning member. Thus, a torsion value of the screwdriver can be set by rotating the sealing cover of the screwdriver.
However, although the conventional screwdriver with fixed torsion has a function of setting a torsion valve, yet the limit of the torsion value set cannot be shown and a user cannot know an accurate torsion value of the screwdriver and hence, the number of circles of turning the sealing cover of the screwdriver must be reset every time when the screwdriver is to be used, inconvenient in use. In addition, the conventional screwdriver with fixed torsion can be adjusted in torsion only by its sealing cover but cannot carry out micro-adjustment when the torsion of the screwdriver is set.